Water inside the Earth is much older than previously thought, study reveals
A recent study of ancient volcanic rocks indicated that water played a decisive role in the constitution of the Earth’s core and in the propulsion of volcanic activities more than three billion years ago.
Scientists from several nations, under the coordination of geochemist Eric Vandenburg, from the University of Adelaide, examined rock formations in the Pilbara Craton, located in Western Australia. The analysis revealed evidence that water penetrated into deep levels of the planet, contributing to the generation of magmas that created volcanoes, similar to those observed today in the Pacific “Ring of Fire”.
The findings, published in the journal Nature Communications, indicate that the Earth already had a water reuse system, analogous to current mechanisms, even in a radically different planetary scenario billions of years ago.
Geochemist Eric Vandenburg highlighted that “the rocks studied were formed in a period more than three billion years ago, when the Earth’s characteristics were quite distinct.” Today, water recycling occurs primarily through plate tectonics, where water from the oceans is drawn into the mantle in areas known as subduction zones.
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However, in the planet’s initial phase, the intense heat prevented the tectonic plates from working in the same way. This raised the question of how surface water managed to reach the depths of the planet more than three billion years ago.
Unraveling the transport of water to the ancient Earth’s mantle
The most recent study points out that, even without the action of modern plate tectonics, an alternative method may have transported water to the mantle. Scientists suggest a mechanism called “dripduction.”
In this dynamic, dense and water-saturated portions of the colder outer crust plunged and broke apart into the incandescent lower mantle, taking the water with them. As this material deepened, water was released, giving rise to magmas that fueled volcanic explosions.
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This discovery contributes to solving one of the most relevant questions in geology: when was the moment when the Earth began the exchange of elements between its surface and the deep underground? Understanding this circulation is vital, as it impacts everything from volcanic manifestations and the formation of continents to the emergence of essential components for sustaining life on the planet.
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Considering the rarity of such ancient rock formations, the Pilbara area stands out as one of the few places suitable for investigating the planet in its initial phase, thanks to the remarkable conservation of its rocks.
By analyzing the chemical impressions present in these rocks, experts reconstructed events from 3.1 billion years ago. The findings indicate that the Earth’s inner and outer regions may have interacted much earlier than expected, showing a young planet, but already active in recycling its water resources.
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